The Synthesis Of Enhanced Photocatalysis Carbon Quantum Dots/Copper-based Nanocomposite And Performance Study

The rapid development of industrial technology,not only has brought great convenience to the life of human beings,but also done a serious threat to the human health.Due to the blindness of development,the protection of the environment was ignored,resulting in most of water resources in the world to be contaminated by organic matter.The traditional technology of sewage treatment was difficult to remove pollutants efficiently and completely.In contrast,semiconductor photocatalytic technology showed satisfactory results in organic degradation and environmental purification.However,the narrow range of light response and the easy recombination of the photo-generated electrons and holes were major problem of the traditional semiconductor materials,which restricted the development of photocatalytic technology.Therefore,it is the major matter to improve the range of light response and reduce the recombination of electron hole pair.And the semiconductor composite technology was the effective way to solve this problem.At the same time,carbon quantum dots?CQDs?have been used in photocatalytic technology widely because of their unique optical properties.Herein,based on the advantages of carbon quantum dots and copper based semiconductors,two nanocomposites of carbon quantum dots/copper sulfide and carbon quantum dots/cuprous oxide were prepared.Two nanocomposites all showed excellent photocatalytic activity,and carbon quantum dots/copper sulfide also showed bacteriostasis for Bacillus subtilis.The main contents of this paper are as follows:?1?The nitrogen-doped carbon quantum dots?CQDs?was obtained through one-pot hydrothermal treatment used ammonium citrate and ethylenediamine as raw materials.The TEM results displayed that the particle size of the carbon quantum dots was uniform.The average diameter and lattice spacing were4.2 nm 0.32 nm respectively.The bright blue fluorescence of CQDs could be seen under the ultraviolet light.And the fluorescence intensity of CQDs cannot be disturbed by the ionic strength,pH and metal ions.The CQDs solution still had high fluorescence intensity after five months under room temperature,which demonstrating the good stability of CQDs.?2?The CQDs/CuS nanocomposite was preparedby one-pot hydrothermal treatment with copper acetate,thiourea,and CQDs solution as raw material.The CQDs/CuS samples were characterized by X-ray diffraction?XRD?,transmission electron microscope?TEM?,fourier transform infrared?FT-IR?,X-ray photoelectron spectroscopy?XPS?,Raman spectra and so on,which proving that carbon quantum dots were attached to the surface of copper sulfide.Then,we explored the photocatalytic activity and mechanism of the nanocomposite.The experimental results indicated the photocatalytic activity of the nanocomposite was higher than that of pure CuS.The possible mechanism was attributed to the CQDs on the surface of CuS,a good electronic storage,which can promote the transfer and separation of the photo-generated electron and holes pair effectively.The antibacterial assays of the CQDs/CuS nanocomposite were evaluated via well-diffusion method.And the results showed that the composite could inhibit the growth of Bacillus subtilis effectively.?3?The pure Cu₂O and CQDs/Cu₂O nanocomposite were synthesized through one-pot hydrothermal treatment respectively.The SEM images showed that the CQDs/Cu₂O nanocomposite had a smaller size compared with the pure Cu₂O,which may be attributed to the function of surfactant and stabilizer the carbon quantum dots acted.The CQDs/CuS samples were characterized by HR-TEM,FT-IR,XPS and so on,which proving that carbon quantum dots were attached to the surface of cuprous oxide successfully.The degradation of methylene blue?MB?and rhodamine B indicated that the photocatalytic activity of the composite was enhanced effectively in comparison to the pure Cu₂O,and the nanocomposite we obtained could be used to degrade dyes widely.